Developing agents are described in Chimie et Physique Photographiques, P Glafkides, Chapter IX, pages 152-170, fifth edition. In general, a principal developing agent is used in association with an auxiliary developing agent. A synergistic effect is observed between the principal developing agent, hereinafter referred to as the "developing agent", and the auxiliary developing agent or "co-developing agent" when the combined activity of the mixture of these two agents is greater than the sum of the activities of each of these agents used separately in the same solution. This phenomena, referred to as "superadditivity" is explained in Mason "Photographic Processing Chemistry", Focal Press, London, 1975.
Di- and polyhydroxyphenols (for example, hydroquinone) and reductones (for example, compounds of the ascorbic acid type) are the developing agents which are most used in practice in black and white developing solutions.
Among the most often used co-developing agents are aminophenols, such as ELON.RTM. (methyl-p-aminophenol sulfate), 1-phenyl-3-pyrazolidones or phenidones, such as phenidone-A (1-phenyl-3 pyrazolidone), phenidone-B (1-phenyl-4 methyl-3-pyrazolidone), dimezone (1-phenyl-4-4'-dimethyl-3-pyrazolidone) or dimezone-S (1-phenyl-4-methyl-4'-hydroxymethyl-3-pyrazolidone). Additional representative examples of aminophenols and phenidones are described in U.S. Pat. No. 2,688,549, U.S. Pat. No. 2,691,589, U.S. Pat. No. 3,865,591, U.S. Pat. No. 4,269,929, U.S. Pat. No. 4,840,879 and U.S. Pat. No. 5,236,816, and by G. E. Ficken and B. G. Sanderson, The Journal of Photographic Science, Vol 11, 1963, pages 157-164.
These co-developing agents have low solubility in water, which presents drawbacks with regard to the manufacture of the developer and its ease of use. In addition, photographic processing solutions are often in the form of powders to be dissolved in water or liquid concentrates to be diluted before use. These powders must be easy to solubilize and the co-developing agents must be sufficiently soluble to enable concentrates to be formulated.
EP-A-528,480 describes a radiographic product comprising a 3-pyrazolidone substituted by a carboxy group directly attached to the phenyl ring. This compound is used as an anti-fogging agent. The radiographic product is developed with a conventional developer comprising hydroquinone and a 1-phenyl-pyrazolidone-1-one co-developing agent.
The problem of the low solubility of phenidone or dimezone-S was resolved in U.S. Pat. No. 4,753,869 by preparing these 1-phenyl-3-pyrazolidones in the form of salts of four particular acids including sulfo groups which dissolve easily in water and are stable during storage. The activity of these compounds in combination with hydroquinone is said to be comparable with that of pyrazolidones which are not in the form of salts.
Zhurnal Nauchnoi i Prikladnoi Fotografii i kinematografii 10, (5), 321-329 (1963) by V. L. Abritalin et al describes photographic developers comprising hydroquinone and a large number of derivatives of 3-pyroazolidones, some of which carry solubilizing groups on the benzene ring. It describes the introduction of the carboxy or sulfo solubilizing groups on the benzene ring to bring a significant reduction in superadditivity. This tendency is also noted by G. E. Ficken and B. G. Sanderson in The Journal of Photographic Science, Vol. 11, 1963, pages 157-160, who report that the introduction of a carboxylic group on the phenidone reduces the superadditivity between phenidone and hydroquinone.
Hydroquinone-based developers generally give good results but present drawbacks with regard to health and the environment. This is why ascorbic acid is used in place of hydroquinone in association with phenidones in developer compositions described in many patents.
Among them, U.S. Pat. No. 5,098,819 describes a developer composition comprising ascorbic acid or its derivatives, and a 3-pyrazolidone compound. The developing agent in the examples contains sodium erythorbate, phenidone or dimezone-S and potassium carbonate. This developer composition is less toxic than those containing hydroquinone and caustic bases and the sensitometric results are close to those obtained with compositions containing hydroquinone.
U.S. Pat. No. 3,938,997 describes a developer solution for the fast development of high-contrast products of the microfilm type. These solutions comprise three developing agents: the first is a ferrous chelate, the second is a compound of the ascorbic acid type, the third is phenidone, GLYCINE.RTM., hydroxylamine sulfate, etc. Developer solutions are obtained which can be easily concentrated.
EP-A-588,408 describes a developer comprising a principal developing agent of the ascorbic acid type and a mixture of two co-developing agents of the phenidone type selected from phenidone-A, phenidone-B and dimezone, dimezone-S. This developer composition makes it possible to obtain improved sensitometric stability which does not depend on the reduction in the pH observed during continuous processing without regeneration. The examples concern emulsions for microfilms.
U.S. Pat. No. 5,264,323 describes compositions for the development of films for graphic arts comprising ascorbic acid or its isomers and a 3-pyrazolidone or aminophenol compound.
EP-A-461,783 describes a developer composition comprising ascorbic acid or its derivatives, a 3-pyrazolidone compound, sulfite or bisulfite and sodium sulfate or glutaraldehyde, that can be used for the development of medical radiographs.
WO 95/00881 describes stable developers comprising a developing agent of the ascorbic acid type or a sugar-type derivative of this acid, and a co-developing agent selected from phenidones and aminophenols (or a mixture of these) for the fast development of graphic arts films incorporating compounds of the hydrazine type.
U.S. Pat. No. 5,384,232 describes developer compositions comprising sodium erythorbate or erythorbic acid associated with dimezone-S for developing lithographic films.
EP-A-603,586 describes formulations of concentrates for developers incorporating a compound of the ascorbic acid type and a co-developer, preferably dimezone-S.
British Patent 1,025,575 describes 1-aryl-3-pyrazolidone developing agents having a 4-CH.sub.2 CO.sub.2 H substituent. While these compounds are reported to have less activity than the unsubstituted corresponding 1-aryl-3-pyrazolidone, their water solubility make them valuable to prepare developers from powdered compositions.
Soviet Patent 265,715 describes a 1-aryl-3-pyrazolidone developing agent with a para-CH.sub.2 CH.sub.2 CO.sub.2 H group on the 1-aryl substituent. The 4-position of the pyrazolidone nucleus is unsubstituted.